Stage 1 – Accumulating snow Sunday morning
A fast-moving “Clipper” low pressure system will spread snow over the Chicago area – beginning early Sunday morning – heaviest snowfall between 4AM and 9AM CST with total snowfall somewhere in the 2 to 4-inch range – a few spots may hit 5-inches. That band of snow should move off to the east by noon.
Stage 2 – Blowing snow/possible Blizzard-like conditions Sunday evening
The cold front moves through late Sunday afternoon or early evening accompanied by a brief burst of snow that could lay down probably less than an additional inch of snow. Behind the front northwest winds strengthen – gusting over 40 miles per hour, blowing and drifting freshly-fallen snow across roadways creating blizzard-like conditions – cutting visibilities to near white-out conditions at times – making travel extremely dangerous.
Stage 3 – Life-threatening Wind Chills of -30 to -45 degrees Monday through Tuesday
As the frigid Arctic-source high pressure follows the cold front into our area overnight Sunday, temperatures will fall dramatically – dropping well below zero Monday morning – resulting in wind chills of -30 to -40 degrees.
Temperatures will stay below zero during the day Monday – then fall even more Monday night – probably reaching -20 degrees Tuesday morning. Gusty northwest winds will continue during this period – 15 to 25 mile per hour with wind chills in the very dangerous -30 to -45 degree range.
The northwest flow Monday into Tuesday will allow the development of lake-effect snow over northwest Indiana and southwestern Lower Michigan.
Subzero temperatures will probably last into the early morning hours Wednesday before southerly winds allow reading to “warm” above zero – reaching into the teens Wednesday afternoon.
Update 9:30AM CST…
As the cold front that produced our overnight snow swings off to the east, the strong pressure gradient associate with the deep low pressure center north of Lake Superior will produce strong northwest winds gusting over 40 miles per hour this morning. The low pressure will continue to pull away to the north and east, loosening the gradient and allowing winds to gradually decrease this afternoon. Cold air will be drawn into the Midwest and western Great Lakes, and our temperatures should be on a steady decline today – dropping through the teens this afternoon into the single digits by this evening.
Winds will become more southerly tonight in advance of the fast-approaching low pressure “Clipper” from the northwest. Temperatures will rise again in advance of this approaching low pressure with snow developing across the region before daybreak Sunday. We are still thinking that a period of accumulating snow – in the 2 to 4-inch range will lay down a fresh blanket of snow before noon. Driving/travel conditions will deteriorate rapidly once the snow sets in early Sunday.
Remnant light snow or freezing drizzle will gradually move east of the area this morning, as a cold front sweeps in from the northwest and temperatures fall into the teens this afternoon and single digits this evening.
Snow Sunday – Wind Chill Watch Monday/Tuesday into Wednesday
A band of snow will precede another “Clipper” low pressure system early later tonight into Sunday forenoon depositing 2 to 4-inches of fresh snow. Frigid Arctic high pressure will follow into our area Sunday night and a Wind Chill Watch has been posted – we will experience strong northwest winds and sub-zero temperatures Monday through Tuesday into Wednesday – calling for dangerous wind chills of -30 to -45-degrees during that period
Snow and blowing snow will cause hazardous driving conditions tonight. A steady snow will spread over the Chicago area tonight ahead of a cold front that will pass through from the northwest during the pre-dawn hours Saturday. About 2 to 3-inches will accumulate. Strong southwesterly winds gusting to 30 miles per hour will precede the front – blowing the falling snow as well as continuing to pick up snow off the ground – creating icy patches on roads as well as sidewalks – drivers and pedestrians alike will need to take extra precautions.
Gusty winds out of the northwest will follow the front with diminishing snow, but still some blowing and drifting into at least mid-morning Saturday. Under partly cloudy skies, winds will quickly die off Saturday afternoon, becoming southerly by evening.
Second Stage – snow Sunday
We hardly catch our breath when a “Clipper” low pressure system sweeps through from the northwest Sunday. Snow will begin here after midnight Saturday and continue through Sunday morning – heaviest snow will probably fall just prior to sunrise and during the forenoon Sunday, with new snow accumulations of 3 to 5 inches possible. Northwest winds will pick up from the northwest, causing more blowing and drifting of snow.
Third Stage – Bitter cold Monday/Tuesday
Probably the coldest surge of Arctic air yet this winter will follow into our area Sunday night with overnight readings falling below zero. This Arctic high pressure will have strong staying-power. Sunday evening may be the last time with above zero temperatures until later next Wednesday. Wind chills of -20 to -30 degrees are likely Monday morning. Monday night/Tuesday morning will probably be the coldest – with the core of frigid air overhead, our low temperatures will most likely fall close to 20-degrees below zero with possible wind chills in the -30 to -45-degree range.
Overnight temperatures bottomed out between 5 and 10-degrees below zero across the Chicago area, and early morning wind chills were about as forecast in the dangerous -15 to -25-degree range. Most temperatures had risen to or above freezing, with clouds overspreading the area and winds were already gusting over 30 miles per hour by 8AM CST this morning.
A winter Weather Advisory is in effect for our area today and tonight calling for hazardous travel conditions to develop due primarily to blowing and drifting snow already on the ground today along with the possibility of some light snow this afternoon. Then additional snow and blowing snow should occur tonight.
Southwest winds are expected to continue to strengthen – gusting consistently over 40 miles per hour this afternoon – picking up the dry snow off the ground and carrying it across roads – especially in open areas – making for unexpected slick spots. These conditions will continue into the nighttime hours.
A cold front is expected to sweep down from the northwest – passing through northeast Illinois, southeast Wisconsin and the northwest Indiana later tonight. Snow will develop ahead of the cold front – winds will remain strong – shifting to the northwest after the front passes a given location. New snow accumulations of 1 to 3 inches are forecast with deteriorating travel conditions likely overnight. Snow should let up and end from the west Saturday morning.
The Wind Chill Advisory remains in effect for the Chicago area (northeast Illinois and northwest corner of Indiana) from 6PM this evening until 10AM CST Friday morning. As temperatures fall steadily overnight – dropping well below zero, and westerly winds hold at 10 to 20 miles per hour – Wind chill readings of -20 to -30-degrees will result.
As southwest winds pick up Friday and temperatures rise, a Winter Weather Advisory will be in place for the Chicago area until 6AM CST Saturday – calling for southwest winds gusting to 30 and 40 miles per hour – with blowing and drifting snow already on the ground. Friday night another 1 to 3-inches of snow along with the blowing and drifting are forecast to occur along and ahead of a cold front sweeping through from the northwest.
Update 12:15PM CST…
After briefly nicking the Chicago lake front, the lake effect snow plume seems to have migrated back out over the central part of Lake Michigan – turning into northwest Indiana (see radar mosaic above) – steered by west to northwest winds. Winds should become more westerly later this afternoon – concentrating the snow plume on the northwest Indiana- southwest Lower Michigan shoreline.
An elongated plume of lake-effect snow developed over central and southern Lake Michigan this morning and will migrate south – impacting the Chicago/Cook County, northwest Indiana, and southwest Lower Michigan shoreline and a short distance inland later this morning and early afternoon..
In concert with the Lake plume, a southward-moving west-east-oriented trough of low pressure will track through southern Lake Michigan inland, giving a period of snow showers along and either side of the trough line. Snowfall amounts of an inch or more per hour could occur as the stronger snow showers near the lake pass over or hold over a given point.
A Wind Chill Advisory is in effect until noon CST today and again from 6PM this evening until 10AM Friday morning for the entire Chicago area. Early morning temperatures were below zero across the region and when combined with northwest winds 15 to 25 mph resulted in wind chills between -20 and -30-degrees.
A look at the National Hazards Map below shows a good portion of the eastern two-thirds of the nation under some form of Wind Chill Advisories/Warnings. Light blue-shaded areas for Wind Chill Advisories (-20 to -30-degree wind chills), and slightly darker-shaded areas depicting Wind Chill Warnings (-35 to -45-degree wind chills) across the Dakotas and Minnesota.
Frost/freeze Warnings covered the Gulf Coast states including much of Florida, and Winter Weather Advisories were in Texas/Louisiana for freezing rain early this morning.
Some Chicago area temperatures/wind chills at 7AM CST…
Location Temp Wind Chill
O’Hare Airport -2 -23
Midway Airport -1 -21
Aurora -4 -28
Waukegan -2 -20
Joliet -3 -22
Du Page Airport -3 -23
Kankakee -4 -25
Morris -3 -26
Romeoville -4 -26
Northerly Island 0 -19
Wheeling -1 -19
Lansing -3 -19
Rockford -5 -24
Rochelle -5 -26
DeKalb -6 -29
Peru -4 -23
National Hazards Map
A wind Chill Advisory is in effect from 9PM CST this evening until 10AM CST Thursday morning for northeast Illinois, southeast Wisconsin and northwest Indiana including the Chicago area for wind chills between -20 and -30 degrees. Prior to that, light snow with around an inch or so accumulation will spread over the area.
Southerly winds and light snow will precede and accompany a cold front sweeping through the Chicago area later this afternoon. Once past a given location, winds will shift to the northwest – with gusts to 30 miles per hour or stronger. A reinforcing Arctic high pressure will follow with overnight temperatures expected to drop below zero. The combination of strong winds and subzero temperatures are forecast to result in the dangerous winds chills later tonight and Thursday morning.
The Weather Center staff is pretty much in concert with the Chicago National Weather Service Forecast Office in the current snowfall forecast. The Weather Service came up with a nice graphic depicting the forecast snowfall amounts (in 2-inch increments) across the Chicago area up until 6PM Tuesday.